1. Field of the Invention
The present invention relates to image processing apparatuses, image processing methods and visual inspection systems and, more particularly, to an image processing apparatus, image processing method and visual inspection system comparing an image of a workpiece to be inspected with a reference image for visual inspection of the workpiece.
2. Description of the Background Art
An image processing apparatus suitable for use as a visual inspection system or the like, which compares an image from an electronic camera with a reference image for providing inspection of workpieces, operates as follows. An input image of a workpiece to be inspected is compared with a reference image in accordance with a comparing program set by a user for visually inspecting the target workpiece for displaying the inspection result onto a video monitor, or to a personal computer, programmable controller or the like.
Generally, examples of inspections performed by the visual inspection system include presence inspection, conformance inspection, orientation inspection, position inspection, dimension inspection, chip and burr inspection, surface defect inspection and the like, which are all common names used at a production line site.
Here, “presence inspection” determines if a component, mark, hole or the like is at a set position on the workpiece. Examples of presence inspection include inspections for missing components on PCBs (Printed Circuit Board), solder on PCB, labels and pills.
“Conformance inspection” inspects to see if a workpiece type agrees with what has been registered. Examples of conformance inspection include quality checks for grade marks and IC (Integrated Circuit) type check by the number of leads.
“Orientation inspection” inspects the direction and front/back orientation of a workpiece. Examples of orientation inspection include checks for IC direction and front/back, label direction, and coil spring orientation.
“Position inspection” finds a position of a specified mark (e.g., hole) and determines if it is within a specified range. Examples of position inspection include checks for PCB positions, LCD (Liquid Crystal Display) registration mark positions, printing positions, labels positions and screw hole positions.
“Dimension inspection” inspects the relation/distance between two specified points to see if they are within a range. Examples of dimension inspection include measurement of bolt lengths and molded object dimensions.
“Chip and burr inspection” inspects for abnormal chips and burrs on the edges of workpieces. Examples of chip and burr inspection include chips and burrs of O rings and molded plastic objects.
“Surface defect inspection” inspects for scratches, dirt and the like in a specified region. Examples of surface defect inspection include checks for pinholes, wrinkles in sheets, air bubbles in LCD panels, cracks in cast metal objects, and dirt in liquids.
Each of these types of inspections has its optimum image comparing program. Thus, a user of this type of image processing apparatus must perform a prescribed setting operation prior to inspection, so that an optimum image comparing program is set according to a target workpiece and a desired type of inspection.
However, the operation of setting the optimum image comparing program according to the target workpiece and the desired type of inspection is highly dependent on the experience and skill of the user. Thus, the user who is not well experienced with this type of image processing apparatus cannot easily perform the prescribed setting operation.